> hi > I'd like to know how the position control works in emc. the pid params > I see are only for axis speed control, what I can't understand is how > emc holds the motor at a particlar position and apply opposing force if > tried to rotate. I was expecting to see pid params for position loop, > but cannot find in any ini file. > tia > Larry
Hi Larry, Look at it this way: EMC only outputs the desired position for each joint (=axis in most cases) each servo period. That's a number that gets updated in real-time. What you do with that number in HAL (the Hardware Abstraction Layer) is up to you (the machine integrator in emc parlance) Some people use steppers driven from the parallel port, so they wire the position command to a step generator, and the output of the step generator to the parallel port driver. Others use servos, so they wire the joint position command to the set-point input of a PID loop. Then wire the motor encoder to the feedback input of the PID, and wire the output of the PID to a hardware driver that actually commands the motor. Some (old?) servos use velocity feedback, but the velocity loop would always have to be surrounded by an outer position loop when used for positioning an axis. Hope this helps, do ask more if anything is unclear. Anders ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
